This invention uses the concepts of true distributed control and distributed device control network of our co-pending applications. It also uses the concepts of device controller and network-enabled devices.
1. Background Field of Invention
This invention relates to device-to-device network communication methods and systems, specifically to device-to-device communications across a hybrid distributed device control network.
2. Background Discussion of Prior Art
The Cambridge Dictionary of American English defines a “device” to be an object or machine invented to fulfill a particular purpose. According to the present invention, the term “device” is not limited to physical apparatus, but is considerably expanded to comprise abstract or virtual devices, such as system operators, that take part in network communications. One fundamental characteristic of devices is that they comprise a finite set of states associated with their operation.
Source routing is packet routing in which a source node has a priori knowledge of the network path to a destination node, i.e., a complete sequence of intermediary network nodes a packet must traverse to reach its destination. This routing information is included in the header of every sent packet.
Source routing is implemented in many network communication environments (e.g., Internet Protocol). Yet, its use is deemed inefficient for regular network package routing due to the overhead of increased packet header size it involves, and it is virtually never used, except for network mapping and troubleshooting instances.
Nonetheless, the simplicity of using source routing communications makes it positively suitable and advantageous for some applications, specifically hybrid distributed device control networks, since its use greatly reduces the cost and complexity of hardware logic of network routing devices and allows for faster networks.
According to the present invention, a hybrid distributed device control network comprises a set of interconnected subnetworks of arbitrary topology, each containing several interconnected device controllers and/or network-enabled devices. The term “hybrid” refers to a network that comprises several subnetworks interconnected across dissimilar communication media (e.g., Ethernet, RF, etc.), and using different communication protocols (e.g., LONtalk, UDP/IP, etc.). Subnetworks using incompatible protocols are interconnected at network routers which act as dual nodes, translating and transferring packets between subnetworks and communication protocols. There are two types of source routing, strict and loose. In strict source routing, every intermediary network node is explicitly specified in the packet header at the source. In loose source routing, a set of intermediary nodes through which the packet must pass are specified in the packet header, but each of these may reside several hops away from one another.
Implementing a communication system over a hybrid distributed device control network using source routing requires simpler processing that results in reduced implementation complexity and cost. Source routing is also compatible with the philosophy of true distributed control because packet routing information is contained at each node where packets originate.
In the recent past, there have been several attempts to create a method of source routing to communicate across hybrid networks (e.g., U.S. Pat. No. 5,570,084). However, the resulting methods are definitely inadequate for device-to-device communications because they do not implement important communications services, namely, multicasting and broadcasting, which are absolutely required for interdevice communications. Other attempts have been made to propose generic methods for routing packets in communications networks (e.g., U.S. Pat. No. 5,353,283). However, the resulting methods either have been developed for networks with limited topologies or cannot be used in networks comprising subnetworks using incompatible communications protocols and/or dissimilar communications media.
Hence, it is an object of the present invention to overcome the disadvantages of the prior art, presenting a source routing communication method specifically designed for interdevice packet routing across networks comprising different communication protocols (e.g., LONtalk, UDP/IP, etc.) and media (e.g., Ethernet, RF, etc.), and providing several communication services.